Spring Forward! When and Why We Observe Daylight Saving Time

March 9, 2019, 12:00 PM UTC

It’s that time of year again. Daylight Saving Time begins on Sunday morning and we all lose an hour of sleep in exchange for the longer daylight hours of spring.

While not every state in the U.S. observes Daylight Saving Time—Arizona and Hawaii take a pass—the rest of us will spring forward this weekend.

Here’s what you need to know before Daylight Saving Time begins:

When is Daylight Saving Time 2019?

More specifically, when do we turn the clocks ahead? Clocks in the U.S. officially change as Daylight Saving Time kicks in at 2 a.m. local time on Sunday, March 10. To save yourself any unnecessary stress and confusion on Sunday, before you go to bed Saturday night, set all your clocks ahead one hour—including the one in your car if it doesn’t change itself. But remember, most smartphones will automatically update themselves when Daylight Saving Time begins.

Who invented Daylight Saving Time?

The origins of Daylight Saving Time are a little blurry as far as who invented it. Some credit the seasonal time changes to scientist George Vernon Hudson and builder William Willett, who proposed shifting the clocks in 1895. Others say Benjamin Franklin invented DST in 1784, but his suggestion wasn’t to change the clocks, it was to get people out of bed earlier—and he was joking.

Why do we observe Daylight Saving Time?

According to Winston Churchill, Daylight Saving Time expands “opportunities for the pursuit of health and happiness” for millions of people by optimizing the daylight hours. But back in 1916, Germany first implemented Daylight Saving Time during World War I when coal was in short supply. The U.S. followed suit during World Wars I and II. And in the 1980s, businesses funded the Daylight Saving Time Coalition because more daylight is better for business. It is also meant to save energy—longer days, in theory at least, translates to less electricity used.

Where is Daylight Saving Time not observed in the U.S.?

States and territories are allowed to individually opt out of observing Daylight Saving Time. In 2019, Arizona, Hawaii, Puerto Rico, Guam, and the U.S. Virgin Islands are the only U.S. states and territories that do not observe Daylight Saving Time.

Daylight Saving Time or Daylight Savings Time?

It’s always Daylight Saving Time. Daylight Savings Time, while often used, is a misspelling.

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